Numerical simulations of dwarf galaxy merger trees

Cloet-Osselaer, A.; Rijcke, S. De; Vandenbroucke, Bert; Schroyen, J.; Koleva, M.; Verbeke, Robbert

doi:10.1093/mnras/stu1071

Cited by 37 publications

(57 citation statements)

References 108 publications

(133 reference statements)

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“…in the cluster environment where large relative velocities make them difficult). However, recently observational evidence has mounted suggesting such mergers (occasionally) happen (in other environments) and simulations have shown them to be a potential way to also form low-mass galaxies (van Zee et al 1998;Bekki 2008;Valcke et al 2008;Martinez-Delgado et al 2012;Graham et al 2012;Cloet-Osselaer et al 2014;Bekki 2015;Pak et al 2016;Watts & Bekki 2016). They were also suggested (in the context of pre-processing in galaxy groups) as a possible origin for KDCs in early-type dwarfs (Toloba et al 2014b).…”

Section: Formation Scenarios For Isolated Early-type Dwarfsmentioning

confidence: 99%

Implications for the origin of early-type dwarf galaxies – the discovery of rotation in isolated, low-mass early-type galaxies

Graham

Forbes

Davies

2017

Monthly Notices of the Royal Astronomical Society

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We present the discovery of rotation in quenched, low-mass early-type galaxies that are isolated. This finding challenges the claim that (all) rotating dwarf early-type galaxies in clusters were once spiral galaxies that have since been harassed and transformed into early-type galaxies. Our search of the Sloan Digital Sky Survey data within the Local volume (z < 0.02) has yielded a sample of 46 galaxies with a stellar mass M ⋆ 5 × 10 9 M ⊙ (median M ⋆ ∼ 9.29 × 10 8 M ⊙ ), a low Hα equivalent width EW Hα < 2Å, and no massive neighbour (M ⋆ 3 × 10 10 M ⊙ ) within a velocity interval of ∆V = 500 km s −1 and a projected distance of ∼ 1 Mpc. Nine of these galaxies were subsequently observed with Keck ESI and their radial kinematics are presented here. These extend out to the half-light radius R e in the best cases, and beyond R e /2 for all. They reveal a variety of behaviours similar to those of a comparison sample of early-type dwarf galaxies in the Virgo cluster observed by Toloba et al. Both samples have similar frequencies of slow and fast rotators, as well as kinematically decoupled cores. This, and especially the finding of rotating quenched low-mass galaxies in isolation, reveals that the early-type dwarfs in galaxy clusters need not be harassed or tidally stirred spiral galaxies.

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Section: Formation Scenarios For Isolated Early-type Dwarfsmentioning

confidence: 99%

Implications for the origin of early-type dwarf galaxies – the discovery of rotation in isolated, low-mass early-type galaxies

Graham

Forbes

Davies

2017

Monthly Notices of the Royal Astronomical Society

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“…Simulations of dwarf-dwarf mergers have recently been presented by Cloet-Osselaer et al (2014) and Deason et al (2014).…”

Section: Companionmentioning

confidence: 99%

“…In particular, its large effective radius might indicate the case (i) of Cloet-Osselaer et al (2014), where a massive progenitor grows with only a few infalling satellites. Future spectroscopic work will lend more clarity.…”

Section: Companionmentioning

confidence: 99%

Isolated elliptical galaxies and their globular cluster systems

Richtler¹,

Salinas²,

Hilker³

et al. 2015

A&A

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Context. Rich globular cluster systems, particularly the metal-poor part of them, are thought to be the visible manifestations of longterm accretion processes. The invisible part is the dark matter halo, which may show some correspondence to the globular cluster system. It is therefore interesting to investigate the globular cluster systems of isolated elliptical galaxies, which supposedly have not experienced extended accretion. Aims. We investigate the globular cluster system of the isolated elliptical NGC 7796, present new photometry of the galaxy, and use published kinematical data to constrain the dark matter content. Methods. Deep images in B and R, obtained with the VIsible MultiObject Spectrograph (VIMOS) at the VLT, form the data base. We performed photometry with DAOPHOT and constructed a spherical photometric model. We present isotropic and anisotropic Jeans-models and give a morphological description of the companion dwarf galaxy. Results. The globular cluster system has about 2000 members, so it is not as rich as those of giant ellipticals in galaxy clusters with a comparable stellar mass, but richer than many cluster systems of other isolated ellipticals. The colour distribution of globular clusters is bimodal, which does not necessarily mean a metallicity bimodality. The kinematic literature data are somewhat inconclusive. The velocity dispersion in the inner parts can be reproduced without dark matter under isotropy. Radially anisotropic models need a low stellar mass-to-light ratio, which would contrast with the old age of the galaxy. A MONDian model is supported by X-ray analysis and previous dynamical modelling, but better data are necessary for a confirmation. The dwarf companion galaxy NGC 7796-1 exhibits tidal tails, multiple nuclei, and very boxy isophotes. Conclusions. NGC 7796 is an old, massive isolated elliptical galaxy with no indications of later major star formation events as seen frequently in other isolated ellipticals. Its relatively rich globular cluster system shows that isolation does not always mean a poor cluster system. The properties of the dwarf companion might indicate a dwarf-dwarf merger.

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“…These simulations are the result of letting isolated proto-galaxies, starting at z = 13.5, merge over time along a cosmologically motivated merger tree (Cloet-Osselaer et al 2014). The result is a galaxy with a relatively well constrained halo mass at z = 0.…”

Section: The Moria Simulationsmentioning

confidence: 99%

A new astrophysical solution to the Too Big To Fail problem

Verbeke

Papastergis

Ponomareva

et al. 2017

A&A

Self Cite

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Aims. We test whether or not realistic analysis techniques of advanced hydrodynamical simulations can alleviate the Too Big To Fail problem (TBTF) for late-type galaxies. TBTF states that isolated dwarf galaxy kinematics imply that dwarfs live in halos with lower mass than is expected in a ΛCDM universe. Furthermore, we want to identify the physical mechanisms that are responsible for this observed tension between theory and observations. Methods. We use the moria suite of dwarf galaxy simulations to investigate whether observational effects are involved in TBTF for late-type field dwarf galaxies. To this end, we create synthetic radio data cubes of the simulated moria galaxies and analyse their H i kinematics as if they were real, observed galaxies. Results. We find that for low-mass galaxies, the circular velocity profile inferred from spatially resolved H i kinematics often underestimates the true circular velocity profile, as derived directly from the enclosed mass. Fitting the H i kinematics of moria dwarfs with a theoretical halo profile results in a systematic underestimate of the mass of their host halos. We attribute this effect to the fact that the interstellar medium of a low-mass late-type dwarf is continuously stirred by supernova explosions into a vertically puffed-up, turbulent state to the extent that the rotation velocity of the gas is simply no longer a good tracer of the underlying gravitational force field. If this holds true for real dwarf galaxies as well, it implies that they inhabit more massive dark matter halos than would be inferred from their kinematics, solving TBTF for late-type field dwarf galaxies.

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Numerical simulations of dwarf galaxy merger trees

Cited by 37 publications

References 108 publications

Implications for the origin of early-type dwarf galaxies – the discovery of rotation in isolated, low-mass early-type galaxies

Implications for the origin of early-type dwarf galaxies – the discovery of rotation in isolated, low-mass early-type galaxies

Isolated elliptical galaxies and their globular cluster systems

A new astrophysical solution to the Too Big To Fail problem

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